# Thread: maths - roots of equation

1. ## maths - roots of equation

for what valus of k does x^2 + (k+2)x + (k+2) = 0 have equal roots??

2. Originally Posted by deej813
for what valus of k does x^2 + (k+2)x + (k+2) = 0 have equal roots??

It has repeated roots at $(k+2)^2-4(k+2)=0$

3. um ok
can you explain how?
so what values of k??

4. Originally Posted by deej813
um ok
can you explain how?
so what values of k??
It will have repeate roots when the discriminat is equal to zero.

The discrimiant is the $b^2-4ac$ part of the quadratic equation(the stuff under the radical)

Solve the above equation to get the "two" values for k (pun intended)

5. so its when k is + or - 2

6. ## roots

You are correct. There will be two parabolas with one root each. Each parabola has a vertex touching the x-axis.